Weird problem

This is a rather weird thing and hard to explain but I'll try my best:

I just formated my computer and all goes well except for one minor thing. When I drag windows around or scroll up and down in them it doesnt do it smoothly, it does it by chunks so it looks kind of laggy. I never had this problem before when my computer was filled with useless chunk cramming it up and now that its good and fresh, I'm experiecing this.

For a better description: When I scroll a web page or drag windows around it looks like I'm playing a game at 5 frames per second.

I hope you guys can understand what I'm trying to say. Does anyone know what the problem might be and ho I can fix it, because I know it will drive me insane very soon. Thanks. Oh yes, by the way- I also switched monitors because my old one just stopped working, so might this be the issue? (The monitor is the same exact model as the last one I had)

512 RAM
128 Video Card
2.0 Processor

 

Install your video drivers